The shadow foreign secretary verbally jousted with First Secretary of State Damian Green, who stood in for Theresa May at the government's dispatch box in the House of Commons on Wednesday 12 July.

Thornberry, one of Labour's chief spokespeople during the general election, tore into the Conservatives over their Brexit plans.

"If the First Secretary of State won't tell the House what 'no deal' means, can he at least clear up the confusion over whether a plan for 'no deal' actually exists?" she asked.

"Yesterday the Foreign Secretary [Boris Johnson] told me that there was no plan for 'no deal'. Two hours later Number 10 fought back and they said there was a plan... The Brexit Secretary [David Davis] might be laughing, I'm coming to him next... the Brexit Secretary was so busy fighting with himself that on March the 12th he said that there was a plan, on March the 17th he said that there wasn't.

"On May the 19th, he said he spent half of his time thinking about it, yesterday he said he wasn't prepared to comment. So, can the First Secretary clear up the confusion today – is there a contingency plan for 'no deal' or isn't there? If there is, will he undertake to publish it?"

Thornberry later mocked May, who used a major post-election speech to urge opposition parties to contribute to the government's Brexit plans, as the UK seeks to split from the EU's single-market and customs union.

"We have a prime minister who is so bereft of ideas that she has started putting suggestion boxes around parliament," the shadow foreign secretary said.

Conservative Councillor, Molly Giles, gave her a backhanded compliment. "Thornberry is much better at PMQs than Corbyn," she said on Twitter. "[It] does make you wonder what the Labour Party has against electing women as leaders."

Emily Thornberry is much better at PMQs than Corbyn. Does make you wonder what the Labour Party has against electing women as leaders. ð

Elsewhere, Business Insider UK politics editor Adam Bienkov said his 80/1 bet on Thornberry to become the next Labour leader was "looking better".

Norman Smith, the BBC's assistant political editor, also weighed in, suggesting that Labour supporters "might hope May [is] away more often" so Thornberry gets to do more PMQs.

But it is extremely unlikely that Corbyn, who helped Labour win 30 extra seats at the election, is going anywhere soon. The latest opinion poll from YouGov, of more than 1,600 people between 5 and 6 July, gave Labour an eight point lead over the Conservatives (46% versus 38%).